Electronic clinical thermometer

ABSTRACT

A temperature sensing unit produces an output signal commensurate with temperature, the output signal serving as a basis for discriminating a temperature above a predetermined threshold temperature as well as a rising temperature gradient over a predetermined period of time. When a discriminator senses both conditions, a temperature measuring unit begins measuring temperature on the basis of an input from the temperature sensing unit. When the measurement begins, the measuring unit raises the resolution of temperature information from the sensing unit.

BACKGROUND OF THE INVENTION

This invention relates to an electronic clinical thermometer and, moreparticularly, to an electronic clinical thermometer which, when broughtinto contact with the surface of a living body, senses that theinstrument is in a state enabling the body temperature to be measured.

With the rapid progress that has been made in semiconductor technology,electronic clinical thermometers have become available in which amicrocomputer, namely a computer mounted on a single chip, isaccommodated in an enclosure of approximately the same size as theconventional glass clinical thermometer. The electronic clinicalthermometer of this type measures and displays body temperature using abattery such as a mercury lithium cell as the power supply. Owing to thelarge power consumption of the microcomputer, however, compactelectronic clinical thermometers that rely upon batteries of a smallcapacity are attended by such problems as the comparatively shortinterval between battery changes and the likelihood of reading errorscaused by run-down batteries. Some conventional electronic clinicalthermometers are provided with a manually operable power switch, whileothers are so designed that the power supply turns on only when ameasurement is actually performd. Electronic clinical thermometers ofthis latter type employ a touch switch or pressure switch in order toeliminate the manual switch operation, or use the touch or pressureswitch in combination with a manual switch in order to reduce powerconsumption by interrupting the flow of current expended in measurementwhenever the thermometer is not actually in contact with the body.

In the touch switch arrangement, it is common practice to use a sensingelement, namely a variable impedance element, such as a capacitor orcoil, of the type which experiences a change in impedance when broughtclose to or in contact with the human body. Since the thermometer isused with a sheath covering the probe associated with the sensingelement, however, the effect of such an arrangement is a marked declinein reliability.

In another aspect, an electronic clinical thermometer equipped with ahigh-impedance contact sensor is adapted to sense the start ofmeasurement by bringing the sensor into contact with the human body.However, owing to such factors as a variance in the thickness of thesheath, a variance in the gap between the sheath and the contact sensoras well as between the sheath and body surface, both reactance-variableand impedance-variable sensors fail to develop a sufficient change inimpedance. Moreover, the sheath itself is electrically insulated. Asensor configuration of the above type therefore does not alwaysguarantee that contact with the human body will be sensed with a highdegree of reliability. Furthermore, touch or contact switches do notnecessarily reduce power consumption to a satisfactory extent, so thatthe problem of rapid battery consumption remains.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been devised to eliminate theabove-described drawbacks encountered in the conventional electronicclinical thermometers, particularly in the sensing means for sensing thestart of body temperature measurement.

The first object of the present invention is to provide an electronicclinical thermometer capable of sensing the start of temperaturemeasurement reliably without responding falsely to a change in ambienttemperature or the like, using as criteria a temperature threshold aswell as a temperature gradient over a predetermined time period.

A second object of the present invention is to realize an electronicclinical thermometer of reduced size and cost by combining theheat-sensitive unit of the device for sensing the start of measurement,with the heat-sensitive unit of the electronic clinical thermometer,thereby enhancing overall reliability and reducing the number ofcomponent parts.

A third object of the present invention is to provide an electronicclinical thermometer which consumes little power, particularly when thethermometer is in a stand-by condition up to the start of measurement.

According to the present invention, the foregoing and other objects areattained by providing an electronic clinical thermometer which comprisestemperature sensing means for producing an output signal commensuratewith temperature, decision means for discriminating, on the basis of theoutput signal of the temperature sensing means, a temperature above apredetermined threshold temperature as well as a rising temperaturegradient over a predetermined period of time, and measuring means placedin a measurement start mode by a discrimination signal from the decisionmeans for initiating a temperature measurement on the basis of an inputfrom the temperature sensing means. The decision means firstdiscriminates a temperature above the threshold temperature and thendiscriminates a rising temperature gradient from the discriminatedtemperature, and comprises an up/down counter for producing an outputsignal commensurate with a temperature sensed by the temperature sensingmeans, and a decoder for producing a first output signal in response toan input signal from the up/down counter indicative of a countcorresponding to a temperature above the threshold temperature, thefirst output signal changing over the counting direction of the up/downcounter so that the counter is counted down by a value commensurate withtemperature within the predetermined period of time, and for producing asecond output signal in response to an input signal from the up/downcounter indicative of a count corresponding to a rising temperaturegradient of a magnitude larger than that of a predetermined risingtemperature gradient, the second output signal establishing themeasurement start mode. The decision means also includes reset means forresetting the value of the count in the up-down counter when the firstoutput signal is not produced, and when the second output signal is notproduced after the production of the first output signal.

In another aspect of the present invention, an electronic clinicalthermometer comprises temperature sensing means for producing an outputsignal, commensurate with temperature, in the form of a digital valueconforming to one of at least two resolutions, one of which is high andthe other low, decision means for discriminating, on the basis of theoutput signal of the temperature sensing means conforming to the lowresolution, a temperature above a predetermined threshold temperature aswell as a rising temperature gradient over a predetermined period oftime, resolution setting means for changing over the resolution of thetemperature sensing means from low to high resolution in response to adiscrimination signal from the decision means, and measuring placed in ameasurement start mode by a discrimination signal from the decisionmeans for initiating a temperature measurement on the basis of thedigital value, conforming to the high resolution, from the temperaturesensing means. The temperature sensing means comprisestemperature-to-frequency converting means, a counter for counting thefrequency and for producing a signal indicative thereof, and resolutionsetting means responsive to an output from the decision means forchanging over the duration of a sampling operation performed by thecounter from a short to a long duration. The decision means comprises anup/down counter for producing an output signal commensurate with atemperature sensed by the temperature sensing means, and a decoder forproducing a first output signal in response to an input signal from theup/down counter indicative of a count corresponding to a temperatureabove the threshold temperature, the first output signal changing overthe counting direction of the up/down counter so that the counter iscounted down within the predetermined period of time by a valuecommensurate with temperature, and for producing a second output signalin response to an input signal from the up/down counter indicative of acount corresponding to a rising temperature gradient of a magnitudelarger than that of a predetermined rising temperature gradient, thesecond output signal establishing the measurement start mode andcontrolling the resolution setting means. The decision means furtherincludes reset means for resetting the values of the count in theup-down counter when the first output signal is not produced, and whenthe second output signal is not produced after the production of thefirst output signal.

Other features and advantages of the invention will be apparent from thefollowing description taken in conjunction with the accompanyingdrawings in which like reference characters designate the same orsimilar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an embodiment of an electronicclinical thermometer according to the present invention;

FIGS. 2a and 2b show, in simplified form, the power supply of theelectronic clinical thermometer and a control section for turning thepower supply on;

FIG. 3 is a flow chart useful in describing control effected by a CPUlocated in a microcomputer shown in FIG. 1;

FIG. 4 is a block diagram illustrating the basic construction of asecond embodiment of the present invention;

FIG. 5 is a block diagram illustrating the embodiment of FIG. 4 ingreater detail;

FIG. 6 is a timing chart useful in describing the operation of thearrangement shown in FIG. 4;

FIG. 7 is a block diagram illustrating an example of the specificconstruction of a device for converting resistance into a pulsefrequency;

FIG. 8 is a block diagram illustrating the details of a control unitshown in FIG. 5; and

FIGS. 9a and 9b are flow charts useful in describing CPU operation andcontrol when the power supply of the microcomputer is turned on.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, an electronic clinical thermometer in thisembodiment of the invention includes a thermister 1 the impedancewhereof changes with temperature, an A/D converter 2 for converting thechange in impedance into a digital quantity, a data bus 3, and amicrocomputer 7 connected to the A/D converter 2 by means of the databus 3. The microcomputer 7 sends the A/D converter 2 a signal, via line4, for setting the resolution (accuracy) of the converter, as well as asignal, via line 5, instructing an A/D conversion. The A/D converter 2sends the microcomputer 7 a signal, via line 6, indicating the end of anA/D conversion. In addition, the microcomputer 7 receives an interruptsignal on line 8, the signal arriving every four seconds, by way ofexample.

The electronic clinical thermometer 10 proper, shown in FIGS. 2a and 2b,is operated by a battery such as a mercury lithium cell constituting apower supply 12. The power supply 12 is connected to a load only whenthe electronic clinical thermometer performs a temperature measurement.When the thermometer is stored in its case 14, the power supply 12 iscompletely cut off from the load, such as a device for sensing the startof a measurement, the microcomputer, etc. To this end, a permanentmagnet 16 is affixed to the case 14, while the interior of theelectronic clinical thermometer is provided with a reed switch, having anormally-open contact 18, at a location where it will be acted upon bythe field from the magnet 16 whenever the thermometer 10 is placed inthe case 14. The circuit connections are such that the contact 18controls the connection between the power supply 12 and the entire load.Thus, when the electronic clinical thermometer 10 is located in its case14, absolutely no power is consumed; when taken out, the load issupplied with power as the conditions demand.

Reference will now be had to FIG. 3, to describe control executed by themicrocomputer 7. In the following discussion we shall assume atemperature gradient of not less than 0.3° C./4 sec. for a four-secondsampling period, and a temperature threshold of 30° C.

When the electronic thermometer 10 is taken out of the case 14, thepower supply 12 is connected to the load automatically, thereby startingthe control sequence and initializing the system (steps S1 and S2).Since a flag (a logical "1" bit) will be established upon the firstrecognition of a temperature measurement of 30° C. or more, logical "0"is set beforehand in one part (hereinafter referred to as FLG) of aregister within a RAM located in the CPU of the microcomputer (step S3).

With a preliminary measurement of temperature performed to detectarrival at the conditions for the start of measurement, a long period oftime is required for the analog-to-digital conversion. In other words,for a preliminary measurement it is unnecessary to measure thetemperature accurately through high resolution which requires highconsumption of power. It is also unnecessary to perform the measurementcontinuously. Accordingly, as shown in step S4 of the flow chart, themicrocomputer 7 sends a logical "0" signal to the A/D converter 2 online 4 to set its resolution in such fashion that a preliminarymeasurement of low accuracy and short sampling duration is performedintermittently every four seconds, by way of example. Next, in step S5,the microcomputer halts the CPU and enters a stopped-state until thenext interrupt.

The CPU starts the control routine for temperature measurement inresponse to an interrupt input which arrives every four seconds, by wayof example, via line 8. Upon the arrival of the interrupt signal, themicrocomputer 7 first applies the A/D conversion command signal to theA/D converter 2 via line 5 (step S1). In step S2, the microcomputerdetermines whether the A/D conversion end signal has been issued by theA/D converter 2; processing shifts to step S3 if it has. If not, step S2is repeated until the decision in step S2 is affirmative. In step S3,the body temperature measured and converted into digital temperaturedata by the A/D converter 2 is read out of the converter 2 by the CPUvia data bus 3 and is registered in a register R1 located in the RAMmentioned above. Step S4 requires a decision as to whether thetemperature data read in by step S3 is indicative of a temperaturehigher than 30° C. When this is not the case, control shifts to step S5where FLG is set to logical "0". In other words, this is a preparatorystep for making the next item of temperature data stored in register R1the first item of data indicative of a temperature of 30° C. or more. Instep S6, the CPU halts to await the next interrupt.

Returning to step S4, let us now assume that the temperature data isfound to indicate a temperature of 30° C. or more, in which case controlmoves to step S7 where it is discriminated whether FLG is logical "0".If it is, the system moves to step S8 which calls for the temperaturedata read in from the converter to be registered in a register R2. Theprocess now moves to step S9 where FLG is set to logical "1", and thento step S10 where the sequence halts to await the next interrupt. Withthe arrival of the next interrupt, processing follows the steps S1through S4 for the reading in of the temperature data. When step S7 isreached, the decision here will be negative since FLG will have been setto logical "1" owing to the process step S9 initiated by the previousinterrupt. The process moves to step S11.

Decision step S11 requires that the last registered temperature data becompared with the current temperature data registered by the latestinterrupt, namely that the arithmetic operation R1-R2 (content ofregister R1 minus content of register R2) be performed to determine thetemperature gradient. It will be understood that this determination ofthe temperature gradient takes place every four seconds since this isthe interval between the interrupt signals. If the condition R1-R2≦0.3°C. is found to hold in step S11, this signifies that the clinicalthermometer is in a condition for performing a meaningfull temperaturemeasurement. The microcomputer 7 therefore delivers a logical "1" signalto the A/D converter 2 on line 4 to raise the converter resolution (stepS12). In other words, the converter 2 is set to sample the temperatureover a longer period of time. The system then shifts to step S13 whichcalls for the CPU to perform an actual measurement of body temperature.When this step is reached, therefore, the four-second interrupt isinhibited.

If the decision rendered in step S11 is negative, indicating that thetemperature gradient over the predetermined time interval is less than0.3° C., the process moves to step S14, which calls for the CPU to setFLG to logical "0". The system moves then to block S15 where thesequence is halted until the next interrupt.

The present invention can also be realized by hard-wired logic, asillustrated in the embodiment of FIG. 4. In this case the electronicclinical thermometer comprises a temperature sensing unit 40 consistingof an element such as a thermister which develops a change in resistancewith temperature, a converting unit 42 for converting the oscillationfrequency of an oscillator into a digital quantity proportional to theresistance of the sensing unit 40, a decision unit 44 for deciding,based on the output data from the converting unit 42, whether thethermometer is in a condition for starting a measurement, and ameasuring unit 46 which starts to perform a temperature measurement onlywhen the decision unit 44 has provided it with a signal indicating thatthe starting condition has been attained. When the decision unit 44provides said signal, the measuring unit 46 delivers a control signal tothe converting unit 42, as indicated by the broken line, therebyestablishing a sampling duration of extended length to raise theresolution of the converter.

The construction and operation of the present embodiment will now bedescibed in greater detail with reference to FIGS. 5 and 6.

As shown in FIG. 1, a thermister 101 for measuring body temperature isconnected to a circuit 102 (hereinafter referred to as a convertingcircuit) for converting resistance into a pulse frequency. Theconverting circuit 102 receives a reference clock signal 106 and aconversion command signal 104 from a control unit 127. When the commandsignal 104 from the control unit 127 goes to logical "1", therebyconstituting a start signal, the converting circuit 102 begins theconversion operation. Signal 104 is sent to logical "0" by a conversionend signal 105 which the converting circuit 102 delivers to the controlunit 127, ending the conversion operation.

The converting circuit 102 may include an oscillator (OSC) theoscillation frequency whereof varies with the reference of thethermister 101, and a control circuit for controlling the oscillation,and is adapted to deliver pulses which the oscillator produces during afixed time interval (namely the conversion time of the convertingcircuit). These pulses constitute the output of the converting circuit102, as will be described below.

The construction and operation of converting circuit 102 may beunderstood from FIG. 7. The control circuit is equipped with aprogrammable timer which, in response to the start signal 104, suppliesthe oscillator OSC with a conversion command of a predetermined durationT1. Upon receiving the signal, the oscillator OSC produces a number ofpulses corresponding to the length of time T1. The control circuitproduces the conversion end signal 105 when the conversion time T1expires. It should be noted that when the control circuit receives ameasurement start signal 125, to be described below, the programmabletimer is set to a value that establishes a conversion time longer thanT1. These measures of time are produced on the basis of the referenceclock signal 106.

Returning to FIG. 5, the abovementioned pulses produced by theconverting circuit 102 exit as a data pulse output signal 103. Thesepulses constitute the clock (CLK) input to a counter 107. The counter107 is of the reversible counting-type and has an up/down (U/D) terminalfor deciding the counting direction. When logical "1" appears atterminal U/D, the counter 107 counts up its clock input. Logical "0" atterminal U/D causes the clock input to be counted down. R denotes thereset terminal of counter 107. The data output 108 of counter 107 isapplied to a decoder 112 as a data input. The decoder 112 is adapted toproduce a logical "1" output on its output terminal T1 upon receivingfrom counter 107 a data input equivalent to 100 pulses, this occurringwhen the thermister 101 senses a temperature of 30° C. A signal appearson output terminal T2 of the decoder 112 when logical "0" is applied tothe U/D terminal of counter 107 and the counter counts down to -3,applying this data to the decoder 112. Numeral 113 denotes the outputsignal obtained from terminal T1. This signal is applied to an AND gate114 whose other input is a decode control signal 129 from the controlunit 127. When the thermister 101 senses a temperature of 30° C. ormore, causing an output to appear on terminal T1 of the decoder 112, andwhen the decode control signal 129 is logical "1", the output signal 117of a divider-by-2 frequency divider 116 goes to logical "1". This signalis applied to the data input of a D-type flip-flop 119. The clock inputto the flip-flop 119 is read pulse 122 produced by the control unit 127in sync with the trailing edge of the conversion command signal 104 inorder that the data input may be stored in the flip-flop 119. With thedata input to flip-flop 119 being logical "1", its Q output, namely anup/down control signal 120, goes to logical "0". The counter 112, whichreceives the Q output at its U/D terminal, is switched over from theup-count to the down-count mode and begins counting down the pulses 103.In addition, a counter reset signal 111 is gated by an AND gate 109 andnot allowed to pass. Accordingly, the data pulse input 103 to thecounter 107 resulting from the next conversion command signal 104 willcount down the counter from the value of the previous up-countoperation.

The final value resulting from the down-count operation will be zerowhen the previously measured temperature and the temperature justmeasured are the same. When the latter is higher, however, counter 107is counted down beyond zero to a negative value. When this value reachesa count of, say, -3 (corresponding to a temperature of +0.3° C.) or amore negative value, an output pulse 123 emerges from terminal T2 ofdecoder 112 and enters a flip-flop 124 which responds by producing asignal 125 indicating that a meaningfull measurement may begin. Thissignal is applied to the converting circuit 102, placing it in a bodytemperature measurement mode and elevating its precision. The signal 125is also applied to the restart terminal of the microcomputer. An ANDgate 133 takes the AND between this signal and an interruption-requestsignal 134 generated every second, whereby the microcomputer 131 isstarted every second from its interrupt-start address.

A measurement start signal 130 from the microcomputer 131 functions as asampling command. When the signal enters the control unit 127, thelatter produces the conversion command signal 104 whereby the valuecorresponding to the temperature measured by the thermister 101 appearsas the output data 108 from counter 107. This value is then read in,operated upon, processed and displayed by the microcomputer 131. At theend of the body temperature measurement, the microcomputer 131 sends ameasurement end signal 128 to the control unit 127 to again establish apre-measurement mode for sensing the start of a measurement. Themicrocomputer 131 again enters a stand-by state at this time to reducepower consumption.

Returning to the state of counter 107, a count of less than -3 (i.e.,-2, -1, 0, +1 . . . ) will not cause the decoder 112 to produce thepulse 123. Flip-flop 124 therefore will not change state, and signal 125will not appear. Since the divide-by-two frequency divider 116 isreceiving the decoded output 115 at the start of the down-countoperation, the output of the frequency divider again changes state atthis time and, in consequence, so does flip-flop 119. The resulting highlevel of signal 120 places the counter 107 in the up-count mode and,with the arrival of signal 111, in the reset state. This re-establishesthe conditions for detection of a temperature of 30° C. or more.

The construction of the control unit 127 is shown in FIG. 8. Numeral 200denotes a power-on reset circuit for producing the reset signal 132 whenpower is introduced to the electronic clinical thermometer 10 of thisembodiment from the power supply 12. Signal 132, as well as being sentto the microcomputer, functions to reset the logic within the controlunit 127. A timer/oscillator circuit 202 delivers the reference clock106 to the converting circuit 102, the clock 106 also being used as acontrol clock for the logic within the control unit 127. By way ofexample, the clock 106 is used by a synchronizing circuit 204,comprising a plurality of flip-flops, to produce the pulses 111synchronized to the clock 106 at the leading edge of its input signal,and is used as a timer counting clock by a counter circuit 206 forproducing the decoder control signal 129. The oscillator circuit 202also produces a clock 208. This serves as a pre-measurement timingclock, set to a period of four seconds, for use in the abovementionedpre-measurement operation of low accuracy. The periods of clocks 106,208 can be set freely by the microcomputer 131. A pre-measurementflip-flop 210 is triggered by the leading edge of the clock 208 andproduces the measurement start signal 104 prior to arrival of the startdetection gate signal 125 via a gate 212. The other input to OR gate 212is the measurement start signal 130 which sends the signal 104, beingproduced after the signal 125 is produced, to logical " 1". An OR gate214 is provided in order that the reset signal 111 for the counters 107,206 may be formed in sync with the command signal 104 or the resetsignal 126 from microcomputer 131. The conversion end signal 105activates the synchronizing circuit 204 which responds by producing theread pulse 122 and, through an OR gate 216, by resetting correspondingflip-flops 210, 222. Reset signals 121 and 126 are produced by an ORgate 220 in response to the power-on reset signal 132 or the measurementend signal 128 from the microcomputer 131.

The circuit shown in FIG. 5 is constructed using C-MOS technology. Atthe instant power is introduced to the circuitry, the counter-set signal111 and flip-flop-reset signals 121, 126 are produced to reset thecounter and flip-flops. The microcomputer 131, on the other hand,receives a reset signal 132 for initialization, upon which themicrocomputer is placed in the stand-by state to suppress powerconsumption.

Reference will now be had to FIGS. 9A and 9 to describe the control ofthe microcomputer 131 when power is introduced.

Referring first to FIG. 9A, the measurement start signal 130 is set to alow level when power is introduced. Next, the measurement end signal 128is set to the low level and the registers are cleared, establishing ahalted state awaiting an interrupt.

In FIG. 9B, the microcomputer 131 has been started by the interruptstart signal 134 generated every second and produces the measurementstart signal 130. Thenceforth the timer is set and the microcomputerawaits for the end of an A/D conversion, i.e., for the conversion oftemperature information into digital data. When the time kept by thetimer expires, the data output 108 on the data bus is read in,computations and processing are executed on the basis of the data, thepredicted temperature is displayed, and so forth. When the bodytemperature measurement ends, the measurement end signal 128 is producedand the CPU is halted. The CPU enters the halted state both after theexecution of prescribed computations and in cases where the temperaturemeasurement has not ended.

For a fuller understanding of the actions of the invention, theoperation of the embodiment shown in FIG. 5 will be described in greaterdetail with reference to the timing chart of FIG. 6.

The conversion command signal 104, namely a pulse having a duration(e.g. 50 milliseconds) equivalent to the conversion time, is deliveredto the converting circuit 102 by the control circuit 127 every fourseconds. The converting circuit 102 produces the data pulse outputsignal 103 upon receiving the conversion command. The read pulse 122 isproduced at the end of each 50-millisecond pulse in the conversioncommand signal 104. Assume not that counter 107 has begun counting thepulses 103 as they are produced by the converting circuit in response tothe command signal 104. If the count does not exceed 100 (signifyingthat the temperature has not reached the threshold of 30° C.), then thedecoded output 113 does not appear. As a result, the circuitry from thefrequency divider 116 onward is inactive. When the second pulse in thecommand signal 104 arrives, the counter 107 again begins counting and,in this case, counts up to a number greater than 100, at which pointlogical "1" appears on output terminal T1 of decoder 112, sending theoutput signal 117 of frequency divider 116 to logical " 1" as well. Theread pulse 122 is produced in response to the conversion end signal 105from the converting circuit 102, and causes the data-type flip-flop 119to store the frequency divider output 117, the Q output of theflip-flop, namely signal 120, going to logical "0". Counter 107therefore is switched over from the up-count to the down-count mode andis counted down by the next series of data pulses 103 produced by theconverting circuit 102 in response to the next conversion command signal104. In the course of being counted down, the value of the count passesthe 100 mark, at which point logical "1" again appears at the outputterminal T1 of the decoder 112. This "1" logic is stored in theflip-flop 119 by the read pulse 122 and sends the up/down control signal120 to logical "1". When the counter reset signal 111 (logical "1")appears, AND gate 119 delivers a pulse since signal 120 is now high,thereby applying a reset pulse to the reset terminals R of counter 107and the divide-by-two frequency divider 116. Counter 107, however, hasnot registered any temperature change. Thus, when the difference betweenthe previous and latest temperature measurements is zero, the resetsignal does not change the state of counter 107 since its content willalready be zero because the up-count and down-count operations will havecancelled each other. It should be noted, however, that counter 107 willbe cleared to zero if it has counted to a negative number of less than-3 (namely -2 or -1). Frequency divider 116 is in the reset mode.

Counter 7 now begins counting up the pulses 103 produced in response tothe next conversion command signal 104. It will be assumed that thecount surpasses 100. The "1" logic on output terminal T1 of decoder 112is stored in flip-flop 119 by the read pulse 122, whereby the up/downcontrol signal 120 is set to logical "0". When the next conversioncommand signal 104 arrives, counter 107 is counted down by the datapulses 103 and, when the 100 mark is passed, terminal T1 of the decodergoes to logical "1". The "1" logic sends the frequency divider output117 to logical "1". In this case, however, we shall assume that asignificant temperature change has been measured by the thermister sothat the counter 107, which is executing the down-count operation,counts down to -3 before the next read pulse 122 is produced. Now, owingto the set conditions, decoder 112 produces a logical "1" signal, namelysignal 123, at its output terminal T2. This signal is applied to theclock input terminal CLK of data-type flip-flop 124 and causes theflip-flop 124 to store its data input, sending its Q output to logical"1". This output signal, namely the start detection gate signal 125, isapplied to the restart terminal of the microcomputer 131 and constitutesa restart signal, thereby starting the microcomputer from apredetermined address.

The present invention, having the construction and operating asdescribed hereinabove, has a number of actions and effects which willnow be set forth.

First, a specific temperature is set up as a threshold, and the start ofan actual body temperature measurement is controlled based upon thedetection of a certain temperature rise, namely a temperature gradient,above the threshold within a predetermined period of time. Accordingly,the electronic clinical thermometer of the invention does not rely upondetection of an impedance change to control the start of measurement,unlike the conventional electronic clinical thermometers, and thereforeis less susceptible to external disturbances when carrying out suchdetection.

Furthermore, in accordance with the present invention, temperature dataat the time of an actual measurement can be obtained from a temperaturesensing unit combined with a unit that delivers temperature dataindicative of the start of measurement. This enables a reduction in thenumber of component parts, contributes to a smaller thermometer, and iseffective in enhancing the precision of both units. Also, since powerconsumption for the pre-measurement can be minimized up to the instantthe beginning of measurement is sensed, the time the power supply isconnected to the load is essentially limited to the time of an actualbody temperature measurement. This allows a single power supply to beexploited to the maximum advantage.

Furthermore, according to the present invention, it is not necessary toprovide a hole or notch for operating the power supply switch on theouter suface of the enclosure, thus the present electronic clinicalthermometer can be designed as a compact thermometer formed integrallyas shown in FIG. 2. Since this construction facilitates cleaning theouter surface of the enclosure and waterproofing so as to prevent aliquid like an antiseptic solution from entering inside the enclosure,it is possible to provide a compact electronic thermometer good both indurability and in sanitary condition.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

What is claimed is:
 1. An electronic clinical thermometer whichcomprises:temperature sensing means for producing an output signalcommensurate with temperature; decision means for discriminating, on thebasis of the output signal of said temperature sensing means, atemperature above a predetermined threshold temperature as well as arising temperature gradient over a predetermined period of time, saiddecision means first discriminating a temperature above the thresholdtemperature and then discriminating a rising temperature gradient fromsaid discriminated temperature; and measuring means placed in ameasurement start mode by a discrimination signal from said decisionmeans for initiating a temperature measurement on the basis of an inputfrom said temperature sensing means; said decision means comprising anup/down counter for producing an ouput signal commensurate with atemperature sensed by said temperature sensing means; and a decoder forproducing a first output signal in response to an input signal from saidup/down counter indicative of a count corresponding to a temperatureabove the threshold temperature, said first output signal changing overthe counting direction of said up/down counter so that said counter iscounted down by a value commensurate with temperature within saidpredetermined period of time, and said decoder producing a second outputsignal in response to an input signal from said up/down counterindicative of a count corresponding to a rising temperature gradient ofa magnitude larger than that of a predetermined rising temperaturegradient, said second output signal establishing the measurement startmode.
 2. An electronic clinical thermometer according to claim 1, inwhich said decision means further includes reset means for resetting thevalue of the count in said up-down counter when said first output signalis not produced, and when said second output signal is not producedafter the production of said first output signal.
 3. An electronicclinical thermometer which comprises:temperature sensing means forproducing an output signal, commensurate with temperature, in the formof a digital value conforming to one of at least two resolutions, one ofwhich is high and the other low, said temperature sensing meanscomprising temperature-to-frequency converting means, and a counter forcounting the frequency and for producing a signal indicative thereof;decision means for discriminating, on the basis of the output signal ofsaid temperature sensing means conforming to the low resolution, atemperature above a predetermined threshold temperature as well as arising temperature gradient over a predetermined period of time;resolution setting means for changing over the resolution of saidtemperature sensing means from low to high resolution in response to adiscrimination signal from said decision mean resolution setting meansbeing responsive to an output from said decision means for changing overthe duration of a sampling operation performed by said counter from ashort to a long duration; and measuring means placed in a measurementstart mode by a discrimination signal from said decision means forinitiating a temperature measurement on the basis of the digital value,conforming to the high resolution, from said temperature sensing means;said decision means comprising an up/down counter for producing anoutput signal commensurate with a temperature sensed by said temperaturesensing means; and a decoder for producing a first output signal inresponse to an input signal from said up/down counter indicative of acount corresponding to a temperature above the threshold temperature,said first output signal changing over the counting direction of saidup/down counter so that said counter is counted down within saidpredetermined period of time by a value commensurate with temperature,and said decoder producing a second output signal in response to aninput signal from said up/down counter indicative of a countcorresponding to a rising temperature gradient of a magnitude largerthan that of a predetermined rising temperature gradient, said secondoutput signal establishing the measurement start mode and controllingsaid resolution setting means.
 4. An electronic clinical thermometeraccording to claim 3, in which said decision means further includesreset means for resetting the value of the count in said up-down counterwhen said first output signal is not produced, and when said secondoutput signal is not produced after the production of said first outputsignal.